Highly sensitive flexible NO2 sensor composed of vertically aligned 2D SnS2 operating at room temperature

Gas sensors for Internet of Things applications should meet two requisites – low power consumption and easy mounting universally. To satisfy the conditions, gas sensors need to operate at lower temperature and be flexible. In this study, we demonstrate a flexible gas sensor operating at room temperature using vertically aligned two-dimensional SnS2 nanomaterials. The atomic layer deposition (ALD) technique allows direct growth of SnS2 on a plastic substrate. The morphological structure of SnS2 is engineered by effecting changes in the growth temperature and substrate surface, which leads to the excellent sensing performance with respect to NO2 gas along with superior gas selectivity. The gas response is as high as 309 at 1 ppm of NO2 at room temperature, and a reliably high response is also observed even below 500 ppb of NO2. The fabricated flexible gas sensor exhibits comparable sensing performance and stability upon bending. Furthermore, the ALD achieves excellent uniformity in both the structural and electrical properties of SnS2 over a 4 in. wafer, which is essential for mass production. Therefore, we believe that this work would contribute to realizing the practical application of highly sensitive flexible gas sensors.